US11947093B2ActiveUtilityA1

Variable magnification optical system and imaging apparatus

Assignee: FUJIFILM CORPPriority: Jun 19, 2020Filed: Jun 18, 2021Granted: Apr 2, 2024

Est. expiryJun 19, 2040(~13.9 yrs left)· nominal 20-yr term from priority

Inventors:Takuya Tanaka Shinkichi Ikeda

G02B 15/20G02B 15/1461

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References

Claims

Abstract

The variable magnification optical system consists of a positive first lens group, an intermediate group, and a subsequent group in order from an object side to an image side, and does not form an intermediate real image in the entire zooming range. During zooming in a first zooming mode, a distance between the first lens group and the intermediate group changes, all distances between adjacent lens groups in the intermediate group change, a distance between the intermediate group and the subsequent group changes, and all distances between adjacent lens groups in the subsequent group are stationary. During zooming in the second zooming mode, all lens groups in the first lens group and the intermediate group are stationary, and all the distances of the adjacent lens groups in the subsequent group change. The zooming in the first zooming mode and the zooming in the second zooming mode can be independent.

Claims

exact text as granted — not AI-modified

What is claimed is: 
     
       1. A variable magnification optical system consisting of, in order from an object side to an image side: a first lens group that has a positive refractive power; an intermediate group that includes a plurality of lens groups; and a subsequent group that includes a plurality of lens groups,
 wherein in a first zooming mode, during zooming, a distance between the first lens group and the intermediate group changes, all distances between adjacent lens groups in the intermediate group change, a distance between the intermediate group and the subsequent group changes, and all distances between adjacent lens groups in the subsequent group are stationary, 
 in a second zooming mode, during zooming, the first lens group and all lens groups in the intermediate group remain stationary with respect to an image plane, and all the distances between the adjacent lens groups in the subsequent group change, 
 zooming in the first zooming mode and zooming in the second zooming mode are possible independently of each other, and 
 an intermediate real image is not formed in an entire zooming range. 
 
     
     
       2. The variable magnification optical system according to  claim 1 , wherein the subsequent group has a positive refractive power as a whole. 
     
     
       3. The variable magnification optical system according to  claim 2 , wherein the subsequent group includes at least one lens group having a negative refractive power and at least one lens group having a positive refractive power in order from the object side to the image side. 
     
     
       4. The variable magnification optical system according to  claim 1 ,
 wherein the subsequent group includes at least one lens group having a positive refractive power, and 
 in a case where a lens group having a strongest positive refractive power among lens groups that move during zooming in the second zooming mode is a SP lens group,
 assuming that βSP is a lateral magnification of the SP lens group in a state where the variable magnification optical system focuses on an object at infinity and the variable magnification optical system is in a zooming state in which a focal length of the variable magnification optical system is shortest, Conditional Expression (1) is satisfied, which is represented by
   −1&lt;β SP&lt;− 0.1  (1).
 
 
 
 
     
     
       5. The variable magnification optical system according to  claim 1 , wherein the subsequent group includes at least one lens group having a negative refractive power,
 assuming that
 fS is a focal length of the subsequent group in a state where the variable magnification optical system focuses on an object at infinity and the variable magnification optical system is in a zooming state in which a focal length of the variable magnification optical system is shortest, and 
 fSN is a focal length of a lens group having a strongest negative refractive power among lens groups that move during zooming in the second zooming mode, 
 Conditional Expression (2) is satisfied, which is represented by
   0&lt; fS/|fSN|&lt; 4  (2).
 
 
 
 
     
     
       6. The variable magnification optical system according to  claim 1 , wherein in a state where the variable magnification optical system focuses on an object at infinity and the variable magnification optical system is in a zooming state in which a focal length of the variable magnification optical system is shortest,
 assuming that
 fw is a focal length of the variable magnification optical system, 
 ωw is a half angle of view of the variable magnification optical system, and 
 Dexpw is a distance on an optical axis from a lens surface closest to the image side in the variable magnification optical system to an exit pupil position of the variable magnification optical system, 
 
 Conditional Expression (3) is satisfied, which is represented by
   0&lt;|{ fw ×tan(ω w )}/Dexpw|&lt;0.2  (3).
 
 
 
     
     
       7. The variable magnification optical system according to  claim 1 , wherein in a state where the variable magnification optical system focuses on an object at infinity and where the variable magnification optical system is in a zooming state in which a focal length of the variable magnification optical system is shortest,
 assuming that
 a focal length of the variable magnification optical system is fw, and 
 a sum of a distance on an optical axis from a lens surface closest to the object side in the variable magnification optical system to a lens surface closest to the image side in the variable magnification optical system and a back focal length of the variable magnification optical system at an air conversion distance is TL, 
 
 Conditional Expression (4) is satisfied, which is represented by
   1&lt; TL/fw&lt; 100  (4).
 
 
 
     
     
       8. The variable magnification optical system according to  claim 1 , wherein assuming that a highest zoom ratio of the variable magnification optical system in the second zooming mode is Zr2max, Conditional Expression (5) is satisfied, which is represented by
   1.2&lt; Zr 2max&lt;3  (5).
 
 
     
     
       9. The variable magnification optical system according to  claim 1 , wherein the first lens group remains stationary with respect to an image plane during zooming in all zooming modes. 
     
     
       10. The variable magnification optical system according to  claim 1 , wherein lens groups that move during zooming in the second zooming mode are two lens groups consisting of a lens group having a negative refractive power and a lens group having a positive refractive power in order from the object side to the image side. 
     
     
       11. The variable magnification optical system according to  claim 1 , wherein lens groups that move during zooming in the second zooming mode are three lens groups consisting of a lens group having a negative refractive power, a lens group having a negative refractive power, and a lens group having a positive refractive power in order from the object side to the image side. 
     
     
       12. The variable magnification optical system according to  claim 1 , wherein lens groups that move during zooming in the second zooming mode are three lens groups consisting of a lens group having a positive refractive power, a lens group having a negative refractive power, and a lens group having a positive refractive power in order from the object side to the image side. 
     
     
       13. The variable magnification optical system according to  claim 1 , wherein lens groups that move during zooming in the second zooming mode are three lens groups consisting of a lens group having a negative refractive power, a lens group having a positive refractive power, and a lens group having a negative refractive power in order from the object side to the image side. 
     
     
       14. The variable magnification optical system according to  claim 4 , wherein Conditional Expression (1-1) is satisfied, which is represented by
   −0.9&lt;β SP&lt;− 0.1  (1-1).
 
 
     
     
       15. The variable magnification optical system according to  claim 5 , wherein Conditional Expression (2-1) is satisfied, which is represented by
   0&lt; fS/|fSN|&lt; 3  (2-1).
 
 
     
     
       16. The variable magnification optical system according to  claim 6 , wherein Conditional Expression (3-1) is satisfied, which is represented by
   0&lt;|{ fw ×tan(ω w )}/Dexpw|&lt;0.1  (3-1).
 
 
     
     
       17. The variable magnification optical system according to  claim 7 , wherein Conditional Expression (4-1) is satisfied, which is represented by
   10&lt; TL/fw&lt; 90  (4-1).
 
 
     
     
       18. The variable magnification optical system according to  claim 8 , wherein Conditional Expression (5-1) is satisfied, which is represented by
   1.3&lt; Zr 2 max&lt;2.2  (5-1).
 
 
     
     
       19. An imaging apparatus comprising the variable magnification optical system according to  claim 1 . 
     
     
       20. The variable magnification optical system according to  claim 1 , wherein the intermediate image of the real image is not formed inside the variable magnification optical system in any state of all zooming states possible in a case where zooming is performed using all the zooming modes of the variable magnification optical system.

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